1、Designation: F3140 17Standard Test Method forCyclic Fatigue Testing of Metal Tibial Tray Components ofUnicondylar Knee Joint Replacements1This standard is issued under the fixed designation F3140; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a procedure for the fatiguetesting of metallic tibial trays used in
3、partial knee jointreplacements.1.2 This test method covers the procedures for the perfor-mance of fatigue tests on metallic tibial components using acyclic, constant-amplitude force. It applies to tibial trays whichcover either the medial or the lateral plateau of the tibia.1.3 This test method may
4、require modifications to accom-modate other tibial tray designs.1.4 This test method is intended to provide useful,consistent, and reproducible information about the fatigueperformance of metallic tibial trays with unsupported mid-section of the condyle.1.5 The values stated in SI units are to be re
5、garded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health and environmental prac
6、tices and deter-mine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides an
7、d Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:E467 Practice for Verification of Constant Amplitude Dy-namic Forces in an Axial Fatigue Testing SystemE468 Practice for Presentation of Constant Amplitude F
8、a-tigue Test Results for Metallic MaterialsE739 Practice for StatisticalAnalysis of Linear or LinearizedStress-Life (S-N) and Strain-Life (-N) Fatigue DataE1823 Terminology Relating to Fatigue and Fracture TestingF1800 Practice for Cyclic Fatigue Testing of Metal TibialTray Components of Total Knee
9、Joint ReplacementsF2083 Specification for Knee Replacement Prosthesis3. Terminology3.1 Definitions:3.1.1 R valuethe R value, also known as the force ratio, isthe ratio of the minimum load to the maximum load. SeeTerminology E1823.R 5minimum loadmaximum load(1)3.2 Definitions of Terms Specific to Thi
10、s Standard:3.2.1 anteroposterior (A/P) centerlinea line that passesthrough the center of the tibial tray, parallel to the sagittal planeand perpendicular to the line of load application.3.2.2 fixture centerlinea line that passes through the centerof the fixture, aligned with the anteroposterior cent
11、erline.3.2.3 mediolateral (M/L) centerlinea line that passesthrough the center of the tibial tray, parallel to the coronal, orfrontal, plane and perpendicular to the line of load application.3.2.4 distance, dapthe perpendicular distance between themediolateral centerline of the tibia component and t
12、he point ofload application.3.2.5 distance, dmlthe perpendicular distance from theanteroposterior centerline of the tibia component to the centerof the load application.4. Significance and Use4.1 This test method can be used to describe the effects ofmaterials, manufacturing, and design variables on
13、 the fatigueperformance of metallic tibial trays subject to cyclic loadingfor relatively large numbers of cycles.4.2 The loading of tibial tray designs in vivo will, in general,differ from the loading defined in this practice. The resultsobtained here cannot be used to directly predict in vivoperfor
14、mance. However, this practice is designed to allow for1This test method is under the jurisdiction of ASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.22 on Arthroplasty.Current edition approved Sept. 1, 2017. Published October 2017.
15、DOI: 10.1520/F3140-17.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for t
16、heDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1comparisons between the fatigue performance of differentmetallic tibial tray designs, when tested under similar condi-tions.4.3 In order for fatigu
17、e data on tibial trays to be comparable,reproducible, and capable of being correlated amonglaboratories, it is essential that uniform procedures be estab-lished.5. Specimen Selection5.1 The test component selected shall have the same geom-etry as the final product, and shall be in processed and fini
18、shedcondition.6. Apparatus6.1 The tibial tray shall be mounted as a three-point bendtest. Care shall be taken to ensure that the three-point bendfixture does not produce abnormal stress concentrations thatcould change the failure mode of the part, especially at the tworeaction locations. The reactio
19、n locations should include cy-lindrical rollers of 6mm diameter to avoid constrained forcesthat will increase the run-out load. Deviation from cylindricalrollers or the suggested diameter shall be justified in testmethods. One possible setup where walls are present on theanterior and posterior locat
20、ions as well as medial lateral centrallocations is shown in Fig. 1. These walls are necessary toprevent a possible rotation or spit-out of the implant during therelatively high frequency fatigue test. Friction between theimplant and the walls should be minimized.6.1.1 The implant shall be placed on
21、the rollers such that thedistance between the centers of rollers shall not be less than80 % of the A/P distance as shown in Fig. 1. The roller contactlengths should overlap with the A/P centerline to minimizemoments causing rotation about the y axis on Fig. 1.6.1.2 The implant should be sufficiently
22、 supported to allowfor bending forces to be applied while minimizing the momentimparted about the A/P or M/L axis that would result in testinstability. In some cases, this location may mask the worst-case M/L load location. An analysis should be conducted tofind the physiological worst-case location
23、 and fixture may needto be designed to accommodate this location.6.2 The tibial tray shall be positioned such that the antero-posterior centerline and the fixture centerline are aligned withan accuracy of 61 mm in the x direction and 62 in the xyplane (see Fig. 1).6.3 When the tibial tray design inc
24、ludes a central keel orother prominence, enough space shall be left under the tray toprevent the keel from impacting during the deflection.6.4 Apply the force by means of a spherical indenter ofeither a diameter of 32 mm or use the femoral component at theFIG. 1 Schematic of Suggested Test SetupF314
25、0 172tibiofemoral flexion angle that generates the smallest contactarea between the femur and the tibial insert observed duringflexion between 0 and 60, whichever is smaller, to be used asworst-case loading condition. A spacer possessing sufficientstiffness and creep resistance (for example, ultra-h
26、igh molecu-lar weight polyethylene, acetal co-polymer) and a recom-mended circular footprint of 13 mm in diameter (see Fig. 2)shall be placed between the tibial tray and the load applicatorto act as a spacer. In the case of semi-constrained or monoblockdesigns it may be more appropriate to use the w
27、orst-casebearing. The choice of bearing used shall be justified in thefinal report. This spacer shall contain an indentation conform-ing to the load applicator. The load applicator shall be aspherical indenter or the intended femoral component fixed ata flexion angle consistent with the curvature re
28、presentative ofthe walking gait contact geometry. The spacer recess shall begreater than or equal to the diameter of the load applicator.6.4.1 The spacer shall be placed on the sulcus point of thetibial condyle. The purpose of the spacer is to distribute theload to the tibial tray condyle and to eli
29、minate possible frettingfatigue initiated by contact between the metal indenter and thetibial tray.6.4.2 The thickness of the spacer, measured at the thinnestpoint between the flat and indented surfaces, shall be no greaterthan the equivalent dimension of the thinnest tibial bearing.6.5 The fixturin
30、g shall be constructed so that the load isapplied perpendicular to the undeflected superior surface of thetibial tray.6.6 Use one of the following two methods for determiningthe position of the loading point.6.6.1 For tibial articulating surface designs that have acurved surface, the loading point s
31、hall be the intersection withthe tray of a line perpendicular to the tray which intersects thedeepest part of the curved recess of the articulating surface ofthe tibial component.6.6.2 For other tibial designs, the femoral component, thetibial articulating surface, and the tibial tray shall be assem
32、bledat 0 flexion and the position of the center of pressuredetermined. The loading point shall be the intersection of theline perpendicular to the tray which intersects the center of thepressure contact area.NOTE 1Optionally, define the worst-case scenario considering thepotential translation in the
33、 transverse plane and/or the potential axialrotation (1)2of the femoral component relative to the tibial baseplate, andapply 6.6.1 or 6.6.2. The rationale for the choice of femoral componentplacement relative to the tibial baseplate should be reported. Femoralloading location that has the potential
34、to generate worstcase stressconcentrations on the fixation features should be considered to address thetrue worst-case loading location.NOTE 2If the geometry of the tibial baseplate superior surfaceprevents using and dapand dmlfor the load application (for example, thepresence of protrusion at the l
35、ocation of the theoretical load application),the rationale for the choice of the appropriate load location should bereported (X1.6 is an example of the variation that could occur due to tibialbaseplate misalignment.) Investigators may elect to use the thinnest tibialinsert in lieu of the spacer for
36、such a situation.6.6.3 The dapand the dmlshall be determined from either ofthe above techniques and will be used for all testing of thatdesign in that size.7. Equipment Characteristics7.1 Perform the tests on a fatigue test machine with ad-equate load capacity.7.2 Analyze the action of the machine t
37、o ensure that thedesired form and periodic force amplitude is maintained for theduration of the test (see Practice E467 or use a validated straingaged part).7.3 The test machine shall have a load and deflectionmonitoring system such as the transducer mounted in line with2The boldface numbers in pare
38、ntheses refer to a list of references at the end ofthis standard.FIG. 2 Suggested Spacer Drawing With Concave Top Surface Cross-section Shown on Bottom Image(Actual dimensions of the spacer may vary as smaller tibial tray designs may require a smaller diameter disk.)F3140 173the specimen. Monitor th
39、e test loads and deflections continu-ously in the early stages of the test and periodically thereafterto ensure the desired load cycle is maintained. Maintain thevarying load as determined by suitable dynamic verification atall times to within 62 % of the largest compressive force beingused. An init
40、ial number of cycles of loading may need to beapplied to reach the desired load parameters before theinitiation of the test.7.3.1 Applied forces outside the 62 % deviation limit at thebeginning of the test will not invalidate the test. However,these cycles shall not be counted toward the completion
41、count.Once counting begins, all cycles must be counted and theapplied forces must remain within the deviation limit.8. Procedure8.1 Determine the size of the tibial tray component used bythe investigator. Dimensions shall be reported.8.1.1 A worst-case analysis shall be conducted and theresulting im
42、plant size(s) tested. A finite element analysis maybe used in this determination.8.1.1.1 Any deviation from the worst-case analysis shall bejustified.8.2 Position the test specimen such that the load axis isperpendicular to the undeflected superior surface of the traysince the tray surface will not
43、remain perpendicular to the loadaxis during loading.8.2.1 For implants that do not have flat superior faces,justify the orientation of the load axis.8.3 Mount the tibial component on the fixture (see Fig. 1).Use the centerline of the tray to align the fixture.8.4 Once aligned, clamp the fixture down
44、 to the testmachine.8.4.1 Use appropriate constraints to the fixture to maintainA/P and M/L axis shown in Fig. 1.8.5 Apply the force by means of a spherical indenter eitherof radius 16 mm or the smallest contact area between the femurand the tibial insert observed during flexion between 0 and60, whi
45、chever is smaller, as worst-case loading conditions.8.6 The magnitude of the load applied and number ofsamples tested are to be established by the user, with justifi-cation. See X1.8.8.7 Test FrequencyRun all tests at a frequency of 20 Hz orless. Take care to ensure that the test machine can maintai
46、n theapplied force at the chosen frequency and that resonantconditions are not reached.8.8 R valueRun all tests with force ratio of 0.1.NOTE 3In strict terms, since the force applied to the tray iscompressive, the maximum force is the smallest negative amplitude.Consequently, the R value is ten when
47、 the negative signs cancel eachother. In terms of applied bending moment at the cantilever plane, the Rvalue would be 0.1. See Terminology E1823 for the definition of the Rvalue (in other words, force ratio).8.9 Record the actuator position throughout the test andreport the maximum deflection.8.10 R
48、eport the test environment used.9. Test Termination9.1 Test shall run until the tibial tray fails or until thepredetermined number of test cycles is reached. The suggestednumber of cycles is ten million. See X1.8.9.1.1 Failure may be defined as a fracture of the tibial tray;formation of a crack dete
49、ctable by eye; fluorescent dyepenetrant, or other non-destructive means; or exceeding apredetermined deflection limit.10. Report10.1 Report the fatigue test specimens, procedures, andresults in accordance with Practice E468.10.2 In addition, report the following parameters: tibial traymaterial, spacer diameter and thickness, indenter diameter orsmallest femoral component contact area at 0-60 degreeflexion, overall anteroposterior and mediolateral dimensions ofthe tray, location of anteroposterior and mediolateral center-lines (for asymmetric tibial trays), tibial co
